TIDUF57 November   2023

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations [Required Topic]
    3. 2.3 Highlighted Products
      1. 2.3.1 LMG3624
  9. 3System Design Theory
    1. 3.1 Quasi-Resonant Operation
    2. 3.2 Transformer Design
    3. 3.3 GaN FET Switching Device
    4. 3.4 Current Sense Emulation Resistor
  10. 4Hardware, Testing Requirements, and Test Results
    1. 4.1 Required Hardware
      1. 4.1.1 Hardware
      2. 4.1.2 Testing Equipment
    2. 4.2 Test Setup
    3. 4.3 Test Results
      1. 4.3.1 Efficiency Results
      2. 4.3.2 Thermal Results
      3. 4.3.3 Switching Waveforms
      4. 4.3.4 Switching Transients
  11. 5Design and Documentation Support
    1. 5.1 Design Files
      1. 5.1.1 Schematics
      2. 5.1.2 BOM
    2. 5.2 Tools and Software
    3. 5.3 Documentation Support [Required Topic]
    4. 5.4 Support Resources
    5. 5.5 Trademarks
  12. 6About the Author

2.3.1 LMG3624

GUID-20230816-SS0I-QHFX-H9SM-VHHDZB6ZFNBR-low.svg Figure 2-2 LMG3624 Functional Block Diagram

The LMG3624 is a 650-V 170-mΩ GaN power FET intended for switch-mode power-supply applications. The LMG3624 simplifies design and reduces component count by integrating the GaN FET and gate driver in a 8-mm by 5.3-mm QFN package.

Programmable turn-on slew rates provide EMI and ringing control. The current-sense emulation feature reduces power dissipation compared to the traditional current sense resistor and allows the low-side thermal pad to be connected to the cooling PCB power ground.

Low quiescent currents and fast start-up times support converter light-load efficiency requirements and burst-mode operation.

Extended feature descriptions are provided in the following list:

  • 650-V, 170-mΩ GaN power FET
  • Integrated gate driver with low propagation delays and adjustable turn-on slew-rate control
  • Current-sense emulation with high bandwidth and high accuracy
  • Cycle-by-cycle overcurrent protection
  • Overtemperature protection with FLT pin reporting
  • AUX quiescent current: 240 μA
  • AUX standby quiescent current: 50 μA
  • Maximum supply and input logic pin voltage: 26 V
  • 8-mm × 5.3-mm QFN package with thermal pad